Imaging overlay targets using moiré elements and rotational symmetry arrangements
US12105433B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 2022 |
| Grant date | Oct 1, 2024 |
| Priority date | — |
| Expiry date | Feb 18, 2042 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/30148
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A metrology target may include a first rotationally symmetric working zone with one or more instances of a first pattern and a second rotationally-symmetric working zone with one or more instances of a second pattern, where at least one of the first pattern or the second pattern is a Moiré pattern formed from a first grating structure with a first pitch along a measurement direction on a first sample layer and a second grating structure with a second pitch different than the first pitch along the measurement direction on a second sample layer. Centers of rotational symmetry of the first and second working zones may overlap by design when an overlay error between the first sample layer and the second layer is zero. A difference between the centers of rotational symmetry of the first and second working zones may indicate an overlay error between the first and second sample layers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.